In particular, Conservative MPs are at odds over whether Britain should seek to remain a member of a customs union with the European Union after it leaves.

Pro-European backbencher Anna Soubry even declared earlier this week that she could quit the Tories if hard-Brexiteers such as Jacob Rees-Mogg seized the leadership.

The poll also gives Theresa May a personal boost, by giving her an eight-point lead over Jeremy Corbyn on the question of which of them would make the best Prime Minister - up from six points last week.

Some 37 per cent back Mrs May, compared to 29 per cent for the Labour leader, while 33 per cent do not know.

However voters overwhelmingly think Mrs May is doing a bad job on negotiating Brexit, with 59 per cent saying she is doing badly, 22 per cent saying she is doing well, while 19 per cent do not know.

There is also a split on the question of whether Britain was right to vote to leave the EU in 2016 with 43 per cent agreeing while 44 per cent disagree.

The same poll last week showed there was a significant, six-point lead for those saying it was wrong to leave.

In a speech to the annual Conservative Black and White Ball, Theresa May vowed to "defeat socialism" and champion "free trade, economic liberalism and the rules-based order".

She said: "Jeremy Corbyn and the Labour party are exploiting populist politics. And what do they offer? Massive renationalisation. Capital flight. A run on the pound. That all leads to a bankrupt Britain.

"That’s why as Conservatives, we are on a renewed mission to fight and win the battle of ideas and to defeat socialism today as we have defeated it before."